Method of construction of three dimensional



y 30, 1961 G. H. NUTTER ETAL 2,985,952

METHOD OF CONSTRUCTION OF THREE DIMENSIONAL BLADING 0F ARBITRARY SHAPEFiled Oct. 9, 195a INVENTORS GEORGE H. NUTTER GLENN M WOOD A T TORNEYUnited States Patent METHOD OF CONSTRUCTION OF THREE DIlVIEN- SIONALBLADING OF ARBITRARY SHAPE George H. Nutter, Manchester, and Glenn M.Wood, East Hampton, Conn., assignors to United Aircraft Corporation,East Hartford, Conn., a corporation of Delaware Filed Oct. 9, 1958, Ser.No. 766,304

7 Claims. (Cl. 29156.8)

This invention relates to bladed impellers and has as its object animproved method of making a master impeller for a pump or the like ofthe type having threedimensional blading. By three-dimensional bladingis meantan impeller having the geometry of its blades so curved ortapered in all dimensions that measurements must be taken from threeplanes each at right angles to the other two in order to locate anypoint on a blade.

The construction of the master impellers for pumps and turbines whichserve as the model for machining or casting operations has been a timeconsuming and painstaking job requiring much hand shaping of the blades.

It is another object of the invention to provide a simplified method formaking these master impellers with greater accuracy.

Still another object of this invention is to provide an improved methodof making the master impeller for pump or turbine impellers havingblading which is very difiicult to shape by usual methods in use.

A further object of the invention is generally to improve the method ofmaking pump and turbine impellers having blading of compound curvature.

These and other objects and advantages of the invention will be evidentor will be pointed out in connection with the following detaileddescription of the preferred embodiment of the invention illustrated inthe accompanying drawing.

In this drawing:

Fig. 1 is a front view and Fig. 2 a side view of a master impeller, orpattern, made in accordance with this invention;

Fig. 3 is a detailed view showing a curved pin.

Figs. 1 and 2 show a master impeller on a shaft including a hub 12 andthre identical impeller blades 14, 16 and 18.

In making the master impeller the hub 12 is turned to the desired shapehaving the required fore and aft curvature shown best in Fig. 2. This isa simple turning operation which can be performed on a lathe. The hub ismade of suitable material which can be turned and bored easily. Aplurality of stations is next established on the hub surface along thelength'of each blade which defines the mean camber line of the blade atits hub end. For purposes of illustration, eight stations have beenshown in the drawing for each blade. In the master impeller constructionshown in Figs. 1 and 2, straight conical pins 20a, 20b, 20c, 20d, 20e,20 20g and 20h are inserted at the eight stations for each blade withtheir longitudinal center lines intersecting the mean camber lines ofthe several impeller blades, here three in number, from the hub to thetip thereof. These pins are also turned from any suitable material andare of correct thick ness and taper to correspond to the tip to hubthickness distribution along the pin center line at each station alongthe blades. It will be understood that each conical pin is inserted atthe proper station corresponding to computed station locations along theblade from the leading edge to the trailing edge thereof.

The tip surface of the blade is generated by varying the length of thetapered pins. A workable filler material is then inserted between thepins and is shaped until all tangent points between adjacent pins arefaired in. This material may be a low melting point metal or ahardenable material, such as plastic wood, which can be worked afterhardening.

Each of the blades of the impeller is made as abovedescribed, all theblades of a given impeller being identical.

In Fig. 3 a pin 22a has been shown which is curved from hub to tip aswould be required to. make an impeller blade in which a line joining themean camber lines of the blade from tip to hub is a curved line.

The method above-outlined would completely describe a hub shape andblade geometry of arbitrary design which can serve as a model forsubsequent machining and casting operations of the impeller.

It will be evident that the method above-described for makingthree-dimensional blade impellers is greatly simplified over previousmethods and eliminates much of the tedious hand shaping of the bladespreviously required.

We claim:

1. The method of making a master impeller for pumps or the like havingthree-dimensional blading which consists in turning an annular hub tothe desired fore and aft curvature, inserting into the surface of saidhub at prescribed stations along each blade location a set of taperedpins of predetermined thickness conforming to the thickness distributionof the blade from tip to hub at said stations, and producing the fullvane geometry of the blades by inserting a workable filler materialbetween the pins and shaping the material to fair in tangent to the pinsurfaces.

2. The method of making a master impeller for pumps or the like havingthree-dimensional blading which consists in, turning an annular hubhaving a fore and aft curvature to produce the desired flow surface,inserting sets of tapered pins of the required thickness to define thetip to hub dimensions of the blades into the surface of said hub at theproper stations along the blades from the leading edge to the trailingedge of the several blades, inserting a workable filler material betweenthe pins, shaping said material until all tangent points betweenadjacent pins are faired in, and generating the tip surface of theblades by varying the length of said pins.

3. The method of making a master impeller for pumps and the like havingthree-dimensional blading which consists in first generating the hubsurface to the desired fore and aft curvature, forming sets of taperedpins for the several blades having the proper thickness along theirindividual lengths to correspond to the tip to hub thicknessdistribution at the various points along the blades,

inserting the formed pins into the hub at the proper stationscorresponding to computed positions along the blades from the leadingedge to the trailing edge of each blade, generating the desired tipsurface of the several blades by cutting off said pins at their freeends, inserting a workable filler material between the pins, and shapingsaid material until all tangent points between adjacent pins are fairedin.

4. The method of making a master impeller for a pump or the like whichconsists in shaping the hub of the impeller to the desired fore and aftcurvature, selecting a plurality of stations along the length of acurved impeller blade each represented by a line joining the mean camberlines from tip to hub of the blade, turning a plurality of tapered plus,one for each of said stations, of the proper thickness along theirlength to correspond to the variable tip to hub thickness distributionof the blade at each station, inserting said pins into said hub at saidprescribed stations, generating the tip surface of the blades by cuttingoff the free ends of said pins, and

inserting a workable filler material between said pins until all tangentpoints between adjacent pins are faired in.

5. The method of making a master impeller for a pump or the like whichconsists in shaping the hub of the impeller to the desired fore and aftcurvature, selecting a plurality of stations along the length of each ofa plurality of curved blades, turning a set of straight conical pins foreach blade of the proper thickness alOng their length to correspond tothe variable tip to hub thickness distribution at each station,inserting the hub ends of said pins into said hub at the prescribedstations for each of said blades, generating the tip surfaces of eachblade by trimming off the pins at their free ends, and inserting aworkable filler material between said pins until all tangent pointsbetween adjacent pins of each set are faired in.

6. The method of making a master impeller for pumps or the like havingthree-dimensional blading which consists in turning an annular hub tothe desired fore and aft curvature, locating a plurality of stations onsaid hub along a curved mean camber line of each blade at the hub end ofthe blades, determining the proper thickness distribution along a hub totip line of the blades at each station, forming tapered pins having thedesired thickness distribution along the hub to tip lines at theselected stations, inserting said pins into said hub at the appropriatestations along each blade from the leading to the trailing edge of theblades, molding a workable filler material between said pins, andshaping said material until all tangent points between adjacent pins arefaired in.

7. The method of making a master impeller for a pump or the like havingthree-dimensional blading, all surfaces of which are curved whichconsists in generating the hub of the impeller to provide the desiredfore and aft curvature, forming a set of longitudinally curved andtapered pins for each blade of the impeller having the proper thicknessalong their lengths to correspond to the tip to hub distribution atvarious stations along the blade from leading to trailing edge of theblade, inserting said pins into said hub with the center lines of theseveral pins of each set joining the mean camber lines from the tip tothe hub of the blade, generating the tip surface of the blades bytrimming the free ends of said pins, molding a workable filler materialbetween the pins, and shaping said filler material until all tangentpoints between adjacent pins are faired in.

References Cited in the file of this patent UNITED STATES PATENTS976,465 De La Hunty Nov. 22, 1910 1,043,175 Van Vrankin Nov. 5, 19121,106,736 Schuler Aug. 11, 1914 2,274,060 Hart Feb. 24, 1942 2,325,617Lysholm et a1. Aug. 3, 1943 2,410,888 Lucy Nov. 12, 1946 2,687,278 Smithet a1 Aug. 24, 1954 2,755,510 Router July 24, 1956 2,836,530 Rees May27, 1958

